Parathion is closely related to which compound?

• A. Methyl parathion
• B. Methyl mercuric chloride
• C. Dichlorvos
• D. Glyphosate

Answer: (A)

Parathion and methyl parathion are chemical analogs within the same class of organophosphate insecticides. They share the same phosphorothioate core attached to a 4-nitrophenyl group, with two alkyl groups on the phosphorus. The difference is simply the alkyl substituents: parathion has two ethyl groups, while methyl parathion has two methyl groups. This makes them very closely related. The other options are a mercury compound, a different herbicide, or an organophosphate with more distinct substituents, so they aren’t as closely related as methyl parathion.